The present invention relates to an energy storage cell as well as to an energy storage module in which a plurality of the energy storage cells are combined. The energy storage cell and the energy storage module are particularly used to supply energy to the drive mechanism of a motor vehicle.
Conventional energy storage cells generally comprise a housing in which the at least one electrochemical element is accommodated. The electrochemical element in the interior of the housing has one anodic connection and one cathodic connection. These two connections are guided outward through the housing and connected to a corresponding anodic and cathodic current tap outside of the housing. The housing usually has a cup-shaped base body, known as the “can.” This cup-shaped base body is closed by use of a cover, known as the “cap.” The anodic and cathodic current taps are located on this cap.
The object of the present invention is to provide an energy storage cell and an energy storage module that may be produced and installed in a cost-effective manner and operated in a low-maintenance, reliable, and efficiency-optimized manner. In particular, the object of the present invention is to provide an energy storage cell and associated energy storage module in which heat from the electrochemical elements may be effectively discharged to the outside.
These and other objects are achieved according to the invention by an energy storage cell comprising an electrically conductive housing, at least one electrochemical element disposed in the housing, an anodic current tap, and a cathodic current tap. The electrochemical element is disposed in the interior of the housing. This element comprises an anodic connection and a cathodic connection. The anodic current tap is located on the exterior of the housing and is directly connected to the anodic connection of the electrochemical element through the housing. The cathodic current tap is also located on the exterior of the housing but is not directly connected to the cathodic connection of the electrochemical element.
According to the invention, the cathodic connection is in contact with the interior of the housing. In turn, the cathodic current tap is also in contact with the housing, such that the current from the cathodic connection is conducted via the electrically conductive housing to the cathodic current tap.
The housing comprises at least three outside walls. The first outer wall is located at a distance from the second outer wall and the third outer wall is disposed in such a way that it closes off the housing and, at the same time, connects the first outer wall to the second outer wall. The anodic current tap is disposed on the first outer wall. The cathodic current tap is either also disposed on the first outer wall or on the third outer wall. In the interior of the housing, the cathodic connection is connected to the second outer wall in an electrically and thermally conductive manner.
The cathodic connection in the interior of the housing, which connects the electrochemical elements to the second outer wall, performs two functions at the same time: the current flow from the electrochemical element via the housing to the cathodic current tap is guaranteed. At the same time, the cathodic connection serves as a direct and very thermally conductive connection between the electrochemical element and the second outer surface. According to the invention, therefore, the heat produced in the electrochemical element can be directly discharged to the second outer surface of the housing via a metal element, namely the cathodic connection. At the same time, the invention ensures that no current tap is located on the second outer surface. For this reason, the second outer surface of the housing may be optimally used for cooling the energy storage cell. The energy storage cell is preferably used in a motor vehicle and is used there for the sole drive or supporting drive of the motor vehicle via an electric motor.
The energy storage cell according to the invention allows the current taps to be disposed on the various outer walls of the housing in a very flexible manner. Thus, the energy storage cells may be combined in various ways to form modules, resulting in a very modular and space-saving structure. At the same time, by virtue of the optimal cooling, the energy storage cells may be operated in a reliable and efficiency-optimized manner. This application will mostly discuss the cooling of the energy storage cells. Naturally, however, it is also possible for heat to be supplied via the second outer wall and the cathodic connection.
It is advantageous for the first outer wall of the housing to at least partially be comprised by a cap. The anodic current tap is preferably disposed on the cap. It is particularly preferred for the cathodic current tap also to be located on the cap. The cap is particularly designed to be large enough that the electrochemical element may be placed in the housing via the corresponding opening. When the cathodic current tap is disposed on the cap, the cap must be at least partially electrically conductive and connected to the rest of the housing in an electrically conductive fashion.
It is advantageous for the housing to have a prismatic design, such that a plurality of energy storage cells may be aligned in a very space-saving fashion. In particular, this is a cuboid structure, with the first outer wall being disposed parallel to the second outer wall. In the case of a cylindrical design of the housing, the first and second outer walls are likewise disposed parallel and at a distance from one another, with the third outer wall forming the shell.
The exterior surface of the second outer wall is preferably electrically insulated. Here, a film is preferably used for insulation. The film should have an extremely thin design that is as thermally conductive as possible. According to the invention, the cooling unit is placed against the second outer wall. Because cooling units are usually made of metal materials, it is advantageous for an electrical insulation to be present between the cooling unit and the second outer wall.
The invention further relates to an energy storage module, in particular for a motor vehicle. The energy storage module comprises at least one of the energy storage cells described above. Any advantageous embodiments discussed in the context of the energy storage cells are correspondingly applicable to the energy storage module as well. Moreover, the energy storage module comprises a cooling unit having a heat transfer surface. This heat transfer surface of the cooling unit rests flush against the second outer wall of the energy storage cell. The advantageous electrical insulation by use of the film is preferably disposed between the heat transfer surface and the second outer wall.
Preferably, a plurality of the energy storage cells are disposed stacked one against the other, with the heat transfer surface of a common cooling unit resting against the plurality of second outer walls of the multiple energy storage cells, such that one cooling unit may be used for multiple energy storage cells.
A fluid conduction device is preferably disposed in the cooling unit. By means of this fluid conduction device, it is possible for the heat from the heat transfer surface to be conducted away toward the outside via the corresponding fluid.
The energy storage cell is preferably embodied as a lithium-ion battery.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.